Well, think of it as going home. Say you are 2.5 miles away from your school, and you need to walk 2.5 more miles to your house, then say it's about to rain. Will you run back to school or to your home? The problem with this is it's close to each number because it's equal. If you add or subtract, you get both answers, so this is a trick question.
<em>SOLUTION: Over the last three evenings, Heather received a total of 109 phone calls at the call center. The third evening, she received 4 times as many calls as the second evening</em>
